用于铬原子光刻的超高真空原子源的研制

原子光刻技术中,良好原子源的产生是最为基础的条件.针对实验中对原子束的具体要求,设计了一套超高真空原子源产生装置,主要参数为:系统工作真空度优于 5.0×10-5Pa,铬原子源温度为1650℃,铬原子最可几速率为960m/s,原子炉口所喷射出的铬原子数为N=1.5×1017s-1.     

Kinetic Control of Long-Range Cationic Ordering in the Synthesis of Layered Ni-Rich Oxides

Deciphering the sophisticated interplay between thermodynamics and kinetics of high-temperature lithiation reaction is fundamentally significant for designing and preparing cathode materials. Here, the formation pathway of Ni-rich layered ordered LiNi_0.6Co_0.2Mn_0.2O₂ (O-LNCM622O) is carefully characterized using in situ synchrotron radiation diffraction. A fast nonequilibrium phase transition from the reactants to a metastable disordered Li_1−x(Ni_0.6Co_0.2Mn_0.2)_1+xO₂ (D-LNCM622O, 0 < x < 0.95) takes place while lithium/oxygen is incorporated during heating before the generation of the equilibrium phase (O-LNCM622O). The time evolution of the lattice parameters for layered nonstoichiometric D-LNCM622O is well-fitted to a model of first-order disorder-to-order transition. The long-range cation disordering parameter, Li/TM (TM = Ni, Co, Mn) ion exchange, decreases exponentially and finally reaches a steady-state as a function of heating time at selected temperatures. The dominant kinetic pathways revealed here will be instrumental in achieving high-performance cathode materials. Importantly, the O-LNCM622O tends to form the D-LNCM622O with Li/O loss above 850 °C. In situ XRD results exhibit that the long-range cationic (dis)ordering in the Ni-rich cathodes could affect the structural evolution during cycling and thus their electrochemical properties. These insights may open a new avenue for the kinetic control of the synthesis of advanced electrode materials.     

Cation Exchange Protocols to Radiolabel Aqueous Stabilized ZnS,ZnSe, and CuFeS2 Nanocrystals with 64Cu for Dual Radio‐ and Photo‐Thermal Therapy

Here, cation exchange (CE) reactions are exploited to radiolabel ZnSe, ZnS, and CuFeS₂ metal chalcogenide nanocrystals (NCs) with ⁶⁴Cu. The CE protocol requires one simple step, to mix the water‐soluble NCs with a ⁶⁴Cu solution, in the presence of vitamin C used to reduce Cu(II) to Cu(I). Given the quantitative cation replacement on the NCs, a high radiochemical yield, up to 99%, is reached. Also, provided that there is no free ⁶⁴Cu, no purification step is needed, making the protocol easily translatable to the clinic. A unique aspect of the approach is the achievement of an unprecedentedly high specific activity: by exploiting a volumetric CE, the strategy enables to concentrate a large dose of ⁶⁴Cu (18.5 MBq) in a small NC dose (0.18 µg), reaching a specific activity of 103 TBq g^?1. Finally, the characteristic dielectric resonance peak, still present for the radiolabeled ⁶⁴Cu:CuFeS₂ NCs after the partial‐CE reaction, enables the generation of heat under clinical laser exposure (1 W cm^?2). The synergic toxicity of photo‐ablation and ⁶⁴Cu ionization is here proven on glioblastoma and epidermoid carcinoma tumor cells, while no intrinsic cytotoxicity is seen from the NC dose employed for these dual experiments.     

克尔媒质中耦合三能级T-C模型中原子信息熵的性质

利用全量子理论,讨论了克尔媒质中耦合V型三能级原子与相干态光场相互作用过程中原子信息熵的演化特性。数值计算结果表明,原子信息熵的演化特性对系统初始时刻场平均光子数的大小很敏感。初始时刻场的平均光子数比较大时,原子信息熵的演化会出现明显的周期性崩塌和回复现象。初态中原子激发态概率幅、原子间耦合强度、失谐量与克尔系数等系统...     

Kerr介质中双模纠缠相干光场与V型三能级原子相互作用系统的原子偶极压缩

研究了Kerr介质中双模纠缠相干光场与V型三能级原子相互作用系统的原子偶极压缩效应，结果表明：此压缩效应和双模纠缠相干光场的纠缠程度、Kerr介质与光场的耦合强度、失谐量及原子初态相关联。